The present invention relates, in general, to an improved surgical biopsy device and, more particularly, to an improved transmission assembly for use in a surgical biopsy device.
The diagnosis and treatment of patients with cancerous tumors, pre-malignant conditions, and other disorders has long been an area of intense interest in the medical community. Non-invasive methods for examining tissue and, more particularly, breast tissue include palpation, X-ray imaging, MRI imaging, CT imaging, and ultrasound imaging. When a physician suspects that tissue may contain cancerous cells, a biopsy may be done using either an open procedure or in a percutaneous procedure. In an open procedure, a scalpel is used by the surgeon to create an incision to provide direct viewing and access to the tissue mass of interest. The biopsy may then be done by removal of the entire mass (excisional biopsy) or a part of the mass (incisional biopsy). In a percutaneous biopsy, a needle-like instrument is inserted through a very small incision to access the tissue mass of interest and to obtain a tissue sample for examination and analysis. The advantages of the percutaneous method as compared to the open method are significant: less recovery time for the patient, less pain, less surgical time, lower cost, less disruption of associated tissue and nerves and less disfigurement. Percutaneous methods are generally used in combination with imaging devices such as X-ray and ultrasound to allow the surgeon to locate the tissue mass and accurately position the biopsy instrument.
Generally there are two ways to percutaneously obtain a tissue sample from within the body, aspiration or core sampling. Aspiration of the tissue through a fine needle requires the tissue to be fragmented into small enough pieces to be withdrawn in a fluid medium. Application is less intrusive than other known sampling techniques, but one can only examine cells in the liquid (cytology) and not the cells and the structure (pathology). In core biopsy, a core or fragment of tissue is obtained for histologic examination which may be done via a frozen or paraffin section. The type of biopsy used depends mainly on various factors and no single procedure is ideal for all cases.
A number of core biopsy instruments which may be used in combination with imaging devices are known. Spring powered core biopsy devices are described and illustrated in U.S. Pat. Nos. 4,699,154, 4,944,308, and Re. 34,056. Aspiration devices are described and illustrated in U.S. Pat. Nos. 5,492,130; 5,526,821; 5,429,138 and 5,027,827.
U.S. Pat. No. 5,526,822 describes and illustrates an image-guided, vacuum-assisted, percutaneous, coring, breast biopsy instrument which takes multiple tissue samples without having to re-puncture the tissue for each sample. The physician uses this biopsy instrument to xe2x80x9cactivelyxe2x80x9d capture (using the vacuum) the tissue prior to severing it from the body. This allows the physician to sample tissues of varying hardness. The instrument described in U.S. Pat. No. 5,526,822 may also be used to collect multiple samples in numerous positions about its longitudinal axis without removing the instrument from the body. A further image-guided, vacuum-assisted, percutaneous, coring, breast biopsy instrument is described in commonly assigned U.S. application Ser. No. 08/825,899, filed on Apr. 2, 1997 and in U.S. Pat. No. 6,007,497. A handheld image-guided, vacuum-assisted, percutaneous, coring, breast biopsy instrument is described in U.S. Pat. No. 6,086,544 and in U.S. Pat. No. 6,120,462. Several image-guided, vacuum-assisted, percutaneous, coring, breast biopsy instruments are currently sold by Ethicon Endo-Surgery, Inc. under the Trademark MAMMOTOME(trademark).
Many breast biopsies done today utilizing image-guided, vacuum-assisted, percutaneous, coring, breast biopsy instruments are still done utilizing x-ray machine. In actual clinical use the biopsy instrument (probe and driver assembly) is mounted to the three axis positioning head of the x-ray imaging machine. The three axis positioning head is located in the area between the x-ray source and the image plate. The stereotactic x-ray machines are outfitted with a computerized system which utilizes two x-ray images, of the breast taken at two different positions to calculate the x, y and z axis location of a suspect abnormality. In order to take the stereo x-ray images the x-ray source must be movable. The x-ray source is, therefore, typically mounted to an arm which, at the end opposite the x-ray source, is pivotally mounted to the frame in the region of the x-ray image plate. In a breast biopsy the breast is placed between the x-ray source and the image plate. In order to take the necessary stereo images, the clinician manually positions the x-ray source on one side and then the other of the center axis of the machine (typically 15-20 degrees to each side of the center axis), obtaining an x-ray image on each side of the breast. The computer will then, calculate the precise x, y and z location of the suspect abnormality in the breast and automatically communicate to the clinician or directly to the positioning head the targeting coordinates for the biopsy device. The clinician can then manually, or automatically, position the biopsy probe into the breast at the precise location of the abnormality.
There are generally two styles of stereotactic x-ray machines in wide spread use for breast imaging. One style is a prone stereotactic x-ray machine, because the patient lies face down on a table during the x-ray and biopsy procedures. The other style, in more wide spread use, is an upright stereotatic x-ray machine. The center axis of the upright imaging machine is vertical to the floor and the patient sits in front of the machine during the x-ray and biopsy procedures.
As described earlier in a stereotactic x-ray machine, the biopsy instrument mounts to a three axis positioning head located between the x-ray source and image plate. The distance between the x-ray source and imaging plate is known in the industry as the SID (Source to Image Distance). There is no standard SID in the industry and, in fact, the SID varies greatly from one x-ray machine manufacturer to another.
It would, therefore, be advantageous to design an image-guided, vacuum-assisted, percutaneous, coring, breast biopsy instrument which may be conveniently be mounted between the x-ray source and image plate of a stereotactic x-ray imaging machine utilizing a minimal amount of space in order to use the breast biopsy instrument with many different types of x-ray machines. It would further be advantageous to design an image-guided, vacuum-assisted, percutaneous, coring, breast biopsy instrument in which the length from the distal tip of the biopsy probe to the most proximal portion of the driver is reduced to less than approximately twenty-nine centimeters. It would further be advantageous to design a remotely driven image-guided, vacuum-assisted, percutaneous, coring, breast biopsy instrument wherein the drive cables for the instrument exit the proximal end of the biopsy instrument driver at an angle which is substantially perpendicular to the central axis of the biopsy instrument in order to minimize the length from the distal tip of the biopsy probe to the most proximal portion of the driver. It would further be advantageous to design a transmission for a remotely driven image-guided, vacuum-assisted, percutaneous, coring, breast biopsy instrument wherein the drive cables for the proximal end of the biopsy instrument driver exit the instrument driver at an angle which is substantially perpendicular to the central axis of the driver in order to minimize the length from the distal tip of the biopsy probe to the most proximal portion of the driver, the transmission converting the motion of the cables to drive the biopsy instrument cutter.
The present invention is directed to a biopsy instrument which includes a base assembly including a firing mechanism, a probe assembly detachably mounted to the base assembly and a drive assembly detachably mounted to the cutter assembly. The probe assembly includes a cutter assembly and a piercer assembly. The cutter assembly includes a cutter and a gear mechanism adapted to move the cutter. The Piercer assembly includes a piercer and a probe mount. The drive assembly includes a flexible drive shaft and a transmission. The transmission includes a first bevel gear operatively connected to a distal end of the flexible drive shaft and a second bevel gear intermeshed with the first bevel gear and operatively connected to the gear mechanism. A medical instrument according to the present invention may further include a coupling alignment sleeve operatively connected to the releasable drive mechanism.
The present invention is further directed to a transmission assembly for a medical instrument wherein the transmission assembly includes a mounting bracket, a transmission plate, a rotation coupling assembly, a translation coupling assembly, a thumbwheel rotation assembly an electrical cable strain relief, a clamping plate assembly, an encoder assembly and a flex relief. The rotation coupling assembly includes a rotation gear and a rotation drive coupling. The translation coupling assembly includes a translation gear and a translation drive coupling. The thumbwheel rotation assembly including a port drive coupling, a first port gear, a second port gear and a knob post. The clamping plate assembly including a rotational bevel gear a translational bevel gear, a rotation shaft and a translation shaft. The encoder assembly including a first bearing assembly which includes a bearing and an encoder. A transmission assembly according to the present invention my further include a gear adapter with and elongated adapter slot operatively connected to the rotation bevel gear.